A friend bought a car at an auction in NJ, only gave them title. He signed, when he went to register in New York they told him he shouldn't have signed. What to do next?

Hello,A friend of mine bought a 2009 Buick Enclave at an auction in New Jersey. They only gave him a signed title from a dealership and the part where the buyer signs was empty, they didn't give him a bill of sale, so when he got home he signed the title. He went to register the car to the DMV in New York and told him he needed a bill of sale, but didn't mention anything about the signature. He got the bill of sale a few days later and went to register the car but they told him they can't register it because he signed the title.I am very confused about this because I understood you were suppose to sign the title of the car. Can someone please help me understand what happened here and also what might be a fast solution to this problem. via /r/cars http://ift.tt/2sedN8i